After going more than a month without a confirmed case of highly pathogenic avian influenza (HPAI) in a commercial poultry flock, the virus has returned.

The United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) reported that the presence of HPAI was confirmed in a commercial duck breeder flock in Fresno County on November 16. There were 53,000 birds in the flock.

This case in Fresno County is the first commercial flock the state has had since October 13, when HPAI was confirmed at a Stanislaus County turkey farm, where 54,900 birds were affected. However, HPAI had been found in a backyard flock in San Diego County earlier in November.

Fresno County previously had five HPAI infections, all of which involved broiler breeders. The last case in the county was confirmed on September 15.


With this latest case, California has had 15 cases of HPAI in commercial poultry flocks in 2022, with a total of 732,500 birds affected. California ranks sixth nationally in terms of flocks affected and 12th in terms of birds lost. These losses have involved broilers, layers, turkeys and ducks.

To learn more about HPAI cases in commercial poultry flocks in the United States and Canada, see an interactive map on 

Read our ongoing coverage of the global avian influenza outbreak.